Ethanol and/or Isopropyl alcohol compositions with at least 60% percent v/v (approximately 52% by weight) are well known to be antibacterial, therefore widely accepted for disinfecting purposes. Nonetheless due to the inherent characteristics of alcohol, it is perceived that the higher the content the better the product and a higher than 60% by volume alcohol content solution is more desirable.
Alcohol disinfectant solutions are generally thickened in order to eliminate the waste and facilitate spreading the composition throughout the desired area. It is also known that other than gelling agents one can use paraffin or waxes to achieve thickening of a solution with high alcohol concentration. Such a composition added with lanolin to reduce the melting point closer to body temperature is described in U.S. Pat. No. 2,054,989. One of the disadvantages of gels and such type thick alcohol containing compositions is that if they do not leave a tacky feeling on the hands after one use (although some do), the effect builds up after repetitive use during the day, making it necessary to eventually wash off the thickeners before continuing the usage of an alcohol antiseptic solution. The present invention if formulated for such type of product does not leave such a feel, and does not need to be washed off after having been used repeatedly.
Another way of thickening high alcohol content solutions has also been taught in U.S. Pat. No. 6,090,395 and 6,623,744 where they use emulsifiers and surfactants as the thickening system to produce a hydroalcoholic lotion with a viscosity of at least 4,000 cps. Also, U.S. Pat. No. 4,956,170 discloses polyethoxylated non-ionic surfactants/emulsifiers to stabilize the added emollient oils in addition to a fatty alcohol although with the addition of a polymeric thickening agent to prepare a hydroalcoholic skin moisturizing/conditioning antimicrobial gel. The disinfecting compositions of the present invention that are gel-like have a viscosity lower than 4,000 cps and no polymeric thickening agent is added.
Generally speaking a high alcohol content disinfectant solution disinfects but does not clean. In order to make them disinfect and clean, so much soap would be needed that the skin would feel soapy and disagreeable, unacceptable for rubbing alcohol purposes. Nonetheless, a non-irritant skin disinfecting high lower alcohol content formulation for use as a skin-washing agent is successfully attained by combining emulsifiers, surfactants and skin emollients to be used as a gel or ointment as described in U.S. Pat. No. 5,629,006.
Surfactants other than for cleaning purposes are also used for spreading an aqueous composition containing one or more active substances rapidly and evenly over a surface due to their wetting properties. The use of good wetting agents definitely improves the efficient use of active substances in different compositions as described in U.S. Pat. No. 5,928,993. Hence, the composition described in the present invention includes the addition of surfactants, specifically fluorosurfactants which are well known for their unparalleled wetting power and which are also surface-active in the lower alcohols used as disinfectant and solvent system in levels which make it acceptable even for rubbing alcohol purposes, providing cleaning, wetting and foaming properties to the composition.
Although a high alcohol content disinfectant solution has good disinfectant characteristics, it has a sharp smell and is generally perceived to cause drying of the skin, characteristics which can also be diminished to a desirable level in the present invention.
A greater than 40% v/v alcohol foam product, easy and safe to use, is desirable over conventional gel or ointment type composition products. The concentration of alcohol already poses a hazard in itself, and there are many applications in which the perceived risk may be diminished if it could be dispensed as a foam without the use of pressurized aerosol containers. A foam intended to be useful as a skin disinfecting agent must have a uniform consistency, spreadability, cleansing ability, and have a pleasant feel, i.e. have rapid breaking power when pressure is applied; all of which present a challenge for a high lower alcohol content composition.
The description of an aqueous foaming skin disinfecting composition using 15% w/w alcohol as a co-solvent, which requires no pressurized container or added propellant to produce the foam, is described in U.S. Pat. No. 3,962,150.
The foam-forming agents utilized heretofore, have been incapable of forming stable foams when the liquid phase has high alcohol content without using other ingredients. Furthermore, lower alcohols have been considered to be defoamers rather than foam-promoting chemicals. According to Klausner, in U.S. Pat. No. 3,131,153, if more than 64% alcohol is used non-homogeneous compositions are obtained. The compositions in the patent required propellant to foam and the foams produced were of limited stability.
Prior to this invention, when a greater than 40% v/v alcohol concentration is required in a product, it is generally accepted that the product will be either liquid or gel, and that if a foam is desired then the concentration of alcohol would need to be reduced or the use of a propellant and a pressurized system would be required.
Surprisingly, in the few “foamable” high alcohol content products disclosed, the types of foam obtained were not similar to those expected from aqueous solutions. The foams obtained are described as fast or aerated foam, quick breaking, with low or limited stability, which would not last for more than one minute, being generally gone within seconds.
It has been disclosed that fluorosurfactants and alcohol can be combined to produce a “stable” foam by a process using high-pressurized means to generate the foam. Highly stable pressurized foams containing high lower alcohol contents and methods of forming and using such pressurized foams in the oil industry using a non-ionic surfactant or mixture of non-ionic surfactants of a specific group of fluorosurfactants are provided in U.S. Pat. No. 4,440,653. The compositions in this patent require the use of a pressurized gas system to generate the foam.
Various examples of compositions with a high lower alcohol content that are dispensed as a foam have been described, although for the purpose of the present invention the characteristics of the foam are not of the desired outcome, since they are fast breaking, of low stability and the foam is produced by means of propellants and aerosol containers only, as the one described in U.S. Pat. No. 5,906,808, which discloses a product that uses an emulsifying wax NF, and a combination of stearyl and cetyl alcohol, or other wax combinations, which improve the foaming performance of the composition, in combination with cetyl lactate, to produce a 0.8% chlorhexidine gluconate alcohol product.
U.S. Pat. No. 5,167,950 issued to Lins discloses a foam product which requires a propellant and no surfactant is added as a cleaning agent. The composition disclosed in this patent is based upon using an emulsifier system (fatty alcohol ROH 16–22 carbons) in combination with the use of a thickening agent (carbomer, klucel, etc.).
U.S. Pat. No. 5,167,950 to Lins discloses an antimicrobial aerosol mousse having a high alcohol content. The mousse comprises alcohol, water, a polymeric gelling agent and a surfactant system comprising a C16–C22 alcohol, aerosol propellant and a non-ionic polyethoxylated surfactant. Despite the work done to date it has been shown that there is little specific knowledge on how foams react and are formed, and surprisingly formulations that might seem not foamable result in the best foam producing ones while other formulations which seemed to have been producing foam even while being prepared did not perform well at all in some non-aerosol foam dispensers. The behaviour of aqueous foams is not the same of that of an alcohol foam.
The traditional ways of forming a gel using polymeric thickeners presents undesirable characteristics and similarly little has been done in forming emulsion-like thickened gels.
It would be very advantageous to have alcohol based disinfecting formulations which may be dispensed as either a gel or a foam. Further, it would be very advantageous and desirable to find a foaming agent that could be used in concentrations that would allow it to be used in products that can remain in the area on which they have been applied and do not need to be rinsed or wiped off due to small amounts of residue remaining after evaporation. Thus it would also be very advantageous to provide foams or gels that do not leave an unpleasant sticky after-feel as most commercial alcohol gel products are known to, or which clog up the dispensing equipment used to dispense the foams and gels.